Molybdenum (Mo) is a widely used trace metal for investigating redox conditions. However, unanswered questions remain that concentration and bulk isotopic analysis cannot specially answer. Improvements can be made by combining new geochemical techniques to traditional methods of Mo analysis. In this Element, we propose a refinement of Mo geochemistry within aquatic systems, ancient rocks, and modern sediments through molecular geochemistry (systematically combining concentration, isotope ratio, elemental mapping, and speciation analyses). Specifically, to intermediate sulfide concentrations governing Mo behavior below the 'switch-point' and dominant sequestration pathways in low oxygen conditions. The aim of this work is to 1) aid and improve the breadth of Mo paleoproxy interpretations by considering Mo speciation and 2) address outstanding research gaps concerning Mo systematics (cycling, partitioning, sequestration, etc.). The Mo paleoproxy has potential to solve ever complex research questions. By using molecular geochemical recommendations, improved Mo paleoproxy interpretations and reconstruction can be achieved.

In one form or another, iron speciation has had a long history as a paleoredox proxy. The technique has been refined considerably over the years, and the most recent scheme is unique in its potential to distinguish three major oceanic redox states - oxygenated, ferruginous and euxinic. This Element covers the theory behind the proxy, methods involved in applying the technique, and potential complications in interpreting Fe speciation data. A series of case studies are also provided, which highlight how more advanced consideration of the data, often in concert with other techniques, can provide unprecedented insight into the redox state of ancient oceans.

The development of multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) makes it possible to precisely measure non-traditional stable isotopes. This volume reviews the current status of non-traditional isotope geochemistry from analytical, theoretical, and experimental approaches to analysis of natural samples. In particular, important applications to cosmochemistry, high-temperature geochemistry, low-temperature geochemistry, and geobiology are discussed. This volume provides the most comprehensive review on non-traditional isotope geochemistry for students and researchers who are interested in both the theory and applications of non-traditional stable isotope geochemistry.

Large igneous provinces (LIPs) are intraplate magmatic events, involving volumes of mainly mafic magma upwards of 100,000 km3, and often above 1 million km3. They are linked to continental break-up, global environmental catastrophes, regional uplift and a variety of ore deposit types. In this up-to-date, fascinating book, leading expert Richard E. Ernst explores all aspects of LIPs, beginning by introducing their definition and essential characteristics. Topics covered include continental and oceanic LIPs; their origins, structures, and geochemistry; geological and environmental effects; association with silicic, carbonatite and kimberlite magmatism; and analogues of LIPs in the Archean, and on other planets. The book concludes with an assessment of LIPs' influence on natural resources such as mineral deposits, petroleum and aquifers. This is a one-stop resource for researchers and graduate students in a wide range of disciplines, including tectonics, igneous petrology, geochemistry, geophysics, Earth history, and planetary geology, and for mining industry professionals.

The Encyclopedia is a complete and authoritative reference work for this rapidly evolving field. Over 200 international scientists, each experts in their specialties, have written over 330 separate topics on different aspects of geochemistry including geochemical thermodynamics and kinetics, isotope and organic geochemistry, meteorites and cosmochemistry, the carbon cycle and climate, trace elements, geochemistry of high and low temperature processes, and ore deposition, to name just a few. The geochemical behavior of the elements is described as is the state of the art in analytical geochemistry. Each topic incorporates cross-referencing to related articles, and also has its own reference list to lead the reader to the essential articles within the published literature. The entries are arranged alphabetically, for easy access, and the subject and citation indices are comprehensive and extensive. Geochemistry applies chemical techniques and approaches to understanding the Earth and how it works. It touches upon almost every aspect of earth science, ranging from applied topics such as the search for energy and mineral resources, environmental pollution, and climate change to more basic questions such as the Earth’s origin and composition, the origin and evolution of life, rock weathering and metamorphism, and the pattern of ocean and mantle circulation. Geochemistry allows us to assign absolute ages to events in Earth’s history, to trace the flow of ocean water both now and in the past, trace sediments into subduction zones and arc volcanoes, and trace petroleum to its source rock and ultimately the environment in which it formed. The earliest of evidence of life is chemical and isotopic traces, not fossils, preserved in rocks. Geochemistry has allowed us to unravel the history of the ice ages and thereby deduce their cause. Geochemistry allows us to determine the swings in Earth’s surface temperatures during the ice ages, determine the temperatures and pressures at which rocks have been metamorphosed, and the rates at which ancient magma chambers cooled and crystallized. The field has grown rapidly more sophisticated, in both analytical techniques that can determine elemental concentrations or isotope ratios with exquisite precision and in computational modeling on scales ranging from atomic to planetary.

In this brief, the authors explore and review the current knowledge regarding the role of molybdenum in the evolution of biological systems and their interaction with biogeochemical cycles. Special emphasis is placed on biological nitrogen fixation and the nitrogen element cycle. The origin and evolution of molybdenum cofactor biosynthetic pathways as well as the evolutionary significance of molybdenum containing enzymes appearance is analyzed. Original data regarding nitrogen fixation pathways and related enzymes molecular evolution processes is presented. The trace element molybdenum is essential for nearly all organisms and forms the catalytic center of a large variety of enzymes such as nitrogenase, nitrate reductases, sulphite oxidase and xanthine oxidoreductases.

How oxygen levels in Earth's atmosphere and oceans evolved has always been a central question in Earth System Science. Researchers have developed numerous tracers to tackle this question, utilizing geochemical characteristics of different elements. Iodine incorporated in calcium carbonate (including biogenic) minerals, reported as I/Ca, is a proxy for dissolved oxygen in seawater. Here we review the rationale behind this proxy, its recent applications and some potential future research directions.

ISOTOPE GEOCHEMISTRY Provides a thorough and up-to-date overview of radiogenic and stable isotope geochemistry Now in its second edition, Isotope Geochemistry presents a comprehensive introduction to radiogenic and stable isotope geochemistry. The first five chapters cover fundamentals including the physics of nuclei, radioactive decay, nucleosynthesis, geochronology, and the theory of stable isotope fractionation. The next chapter focuses on the isotope geochemistry of meteorites and their constraints on the formation of the solar system and the Earth. The subsequent three chapters cover radiogenic and stable isotope geochemistry evolution of the Earth’s mantle and crust. Three more chapters are devoted to the Earth’s surface, the exogene, including the hydrologic system, the biosphere, and climate. A new chapter in this edition focuses on the use of isotopes in paleontology and archeology. The final chapter is devoted to the isotope geochemistry of the noble gases. Illustrated in full color throughout, Isotope Geochemistry is intended primarily as a textbook for advanced undergraduate and graduate students. It is also intended as a reference for earth science professionals, reflecting the impact that isotope geochemistry has on virtually every aspect of the earth sciences, from climate change and geomorphology to geodynamics.